In fields such as mobile telephony and communication, it is being proposed that radio frequency transceivers operating in different frequency bands, and providing different services, should be integrated into single consumer devices.
For example, in order to improve the coverage area in which a mobile telephone can be used, a satellite system transceiver, a terrestrial transceiver and a domestic cordless telephone transceiver might be integrated into one hand-held unit. An alternative example is a dual service telephone operating at 1800 MHz in the user's home country but having the capability of operating at 900 MHz in other countries under a so-called roaming arrangement.
The electronics needed to achieve this aim are rapidly becoming smaller and lighter. A remaining problem area for multi-frequency, multi-system operation, however, is the antenna.
In order to operate as described above, an antenna should be able to work at different frequencies and with different types of base station. For example, one service may use terrestrial base stations and another may use orbiting satellites. This means that if the handset antenna is typically used in a vertical position (with the handset held next to the user's head) then for one service the antenna should have a radiation pattern substantially omnidirectional in azimuth and for the other service it should have an approximately hemispherical radiation pattern.